A script coloring the content of a binary file

Show-File.ps1

param (
    [Parameter(Position = 1, Mandatory = $True)]
    [ValidateScript({ Test-Path $_ })]
    [String]$Path,
    [Int64]$Offset = 0
)

$ErrorActionPreference = "Stop"

$Colors = @(
    [ConsoleColor]::Black,
    [ConsoleColor]::White,
    [ConsoleColor]::Blue,
    [ConsoleColor]::Green
)

if ($Host.UI.RawUI.WindowSize.Width -lt 20 -or $Host.UI.RawUI.WindowSize.Height -lt 10) {
    Write-Error "The console window is too small."
}

$ColorsPerByte = 4
$rawUI = $Host.UI.RawUI
$maxWidth = $rawUI.WindowSize.Width - ($rawUI.WindowSize.Width % $ColorsPerByte)

function Write-EncodedBytes {
    param(
        [byte[]]$data,
        [int]$start,
        [int]$cnt)

    for ($i = 0; $i -lt $cnt; $i++) {
        $b = $data[$start + $i]
        $rawUI.BackgroundColor = $Colors[(($b -band 0xC0) -shr 6)]
        Write-Host -NoNewline ' '
        $rawUI.BackgroundColor = $Colors[(($b -band 0x30) -shr 4)]
        Write-Host -NoNewline ' '
        $rawUI.BackgroundColor = $Colors[(($b -band 0xC) -shr 2)]
        Write-Host -NoNewline ' '
        $rawUI.BackgroundColor = $Colors[($b -band 0x3)]
        Write-Host -NoNewline ' '
    }
}

function Write-Header {

    param ([int]$FileLength)

    Clear-Host

    $availConsoleLines = $rawUI.WindowSize.Height - 1

    # intial header lines
    $rawUI.BackgroundColor = [ConsoleColor]::Green
    1..4 | Foreach-Object {
        1..($maxWidth) | Foreach-Object { Write-Host -NoNewline ' ' }
        Write-Host
        $availConsoleLines--
    }

    # draw all possible colors
    $Colors | ForEach-Object {
        $rawUI.BackgroundColor = $_;
        Write-Host -NoNewline '   '
    }
    Write-Host; $availConsoleLines--

    # encode screen width and height
    $b = [BitConverter]::GetBytes($maxWidth)
    Write-EncodedBytes $b 0 $b.Length
    $b = [BitConverter]::GetBytes($rawUI.WindowSize.Height)
    Write-EncodedBytes $b 0 $b.Length
    Write-Host; $availConsoleLines--

    # write line of colors for validation
    $b = @(0x1b) # 00011011
    1..([int]($maxWidth / $ColorsPerByte)) | ForEach-Object { Write-EncodedBytes $b 0 1 }
    Write-Host; $availConsoleLines--

    # encode file length
    $b = [BitConverter]::GetBytes($FileLength)
    Write-EncodedBytes $b 0 $b.Length
    Write-Host; $availConsoleLines--

    # fill the rest of the console screen
    while ($availConsoleLines -gt 0) {
        Write-Host; $availConsoleLines--
    }
}

$md5 = [System.Security.Cryptography.MD5]::Create()

function Write-Hash {
    param (
        [byte[]]$data,
        [int]$cnt
    )

    $hash = $md5.ComputeHash($data, 0, $cnt)
    Write-EncodedBytes $hash 0 $hash.Length
    Write-Host
}

function Write-ScreenEnding {

    $rawUI.BackgroundColor = $Colors[$script:lastEndingColor]
    1..($rawUI.WindowSize.Width - 1) | Foreach-Object { Write-Host -NoNewline ' ' }
    $resp = Read-Host
    $script:lastEndingColor = ($script:lastEndingColor + 1) % $Colors.Length

    $resp -eq "n"
}

$prevBackground = $rawUI.BackgroundColor

$Path = Resolve-Path $Path
$f = [IO.File]::OpenRead($Path)
$f.Seek($Offset, [System.IO.SeekOrigin]::Begin) | Out-Null

$lastEndingColor = 0

Write-Header $f.Length
Write-ScreenEnding | Out-Null

$windowSize = $rawUI.WindowSize
$data = New-Object byte[] ([int]($maxWidth * ($windowSize.Height - 2) / $ColorsPerByte))
$linelen = [int]($maxWidth / $ColorsPerByte)
$cnt = $data.Length

while ($cnt -eq $data.Length) {
    $cnt = $f.Read($data, 0, $data.Length)

    do {
        $bytesleft = $cnt
        for ($line = 0; $line -lt $windowSize.Height - 2; $line++) {
            if ($bytesleft -gt 0) {
                Write-EncodedBytes $data ($line * $linelen) ([Math]::Min($linelen, $bytesleft))
                $bytesleft -= $linelen
            }
            Write-Host
        }
        Write-Hash $data $cnt
    } while (-not (Write-ScreenEnding))
}

$f.Dispose()

$rawUI.BackgroundColor = $prevBackground

Get-FileHash $Path